Positron Emission Tomography (PET) using 18F-2-deoxyglucose (FDG) allows us to obtain anatomical data (e.g., axial transverse or coronal images of the brain) as well as dynamic functional data (such as regional cerebral glucose consumption rate, and measurement of storage, degradation and turnover of tagged metabolites and neuroligands). Besides FDG, other radiopharmaceuticals (tagged with 18F, 150, 11C 13N) can be used with PET to study the BBB, oxygen metabolism, protein synthesis, and neuroreceptors. The unique property of PET is that it provides physiologic and pathophysiologic information not available with any other imaging procedure.